German Patent Application Publication No. DE 197 13 884 A1 relates to a method for controlling the headlight range and/or the illuminating direction of headlights in a vehicle. Sensors collect data on the vehicle and its surroundings. Based on these data, the current headlight setting of the headlights of the vehicle are adjusted prospectively to the requirements for illuminating the roadway lying ahead of the vehicle. The at least one sensor used is particularly a video sensor, which takes images of the course of the roadway which, in turn, are evaluated by an image evaluation unit. The illumination range of the headlights is controlled by determining the pitch angle of the vehicle with respect to the roadway. The pitch angle is ascertained via a plane determination of the roadway. By determining the yaw angle between vehicle and roadway, as well as the course of the roadway lying ahead of the vehicle, the horizontal illuminating direction and/or the illumination range of the headlights is regulated.
The headlights of other vehicles are detected by the image evaluation unit, and when the headlights are set to high beam, the headlights are automatically dimmed, or otherwise a warning is output to the driver of the vehicle. The detection of other vehicles is performed by evaluating the data of the at least one video sensor with the aid of an estimate of the image shift.
The data of the at least one sensor, particularly of the at least one video sensor, are checked in the image evaluation unit, the headlights being set to a stationary output position, if no meaningful parameters for setting the headlights are able to be derived from the data.
At night, in video systems that include, for instance, the above-mentioned video sensor, and which have wide-angle cameras, close objects which are located laterally next to the traveling vehicle can no longer be detected, and this applies especially to traffic signs, but also to persons. This happens because the illumination of the headlights is not sufficient. The dimmed light of a vehicle tends to radiate in a flat manner and little goes sideways. When the vehicle is traveling, the image explosion increases towards the edge. This particularly leads to a great increase in the motional unsharpness of objects located on the roadway edge, such as traffic signs or people present at the edge of the roadway. A remedy would be to reduce the exposure time. However, reduction in the exposure time goes along with a reduction in the contrast in the night vision system, which is also not beneficial to the detection performance of this system. Video systems, within the scope of night vision systems or the like, used in the present connection, include wide-angle cameras. In the present connection, one should understand by wide angle that the aperture angle of the video camera is greater than that of the headlights.